Call distributing telephone system



June 7, 1932. w. T. miami/ELL. 1,861,754

CALL DISTRIBUTING TELEPHONE SYSTEM Filed Aug. 10, 1929 l. 9 Sheets-Sheet l di 0 n.

m E n n n u U LU uJ m P' Iun m E '0 1 ..1

INVENTOR WNFRED T. POWELL ATTORN EY June 7, 1932.

SECTKBNS LAMPS JAcKs W. T. POWELL CALL DISTRIBUTING TELEPHONE SYSTEM Filed Aug. 10, 1929 9 Sheets-Sheet 2 GLENwooD EXQHANGE B 'wwcHBoARD INVENTOR 'WNFEED T. POWELL BY MW ATTORN EY June 7, w. T. POWELL 1,861,754

CALL DISTRIBUTING TELEPHONE SYSTEM INVENTOR WlNFEED T. POWELL.

ATTORNEY v W. T. POWELL June 7, 1932.

CALL DISTRIBUTING TELEPHONE SYSTEM Filed Aug. l0, 1929 9 Sheets-Sheet 4 .NOPUNJNW v/N DZOUN o ooooo oooo O O oooco oooo E w. 0 RP mm. ma IW... W Y B 50H6 no ATTORN EY June 7, 1932.

W. T. POWELL CALL DISTRIBUTING TELEPHONE SYSTEM Filed Aug. 10, 1929 La n 9 Sheets-Sheet 5 INVENTOR WINFRED T. POWELL ATTOR N EY 12.3456789WHI2I5I4I5 June 7, 1932. v w T POWELL 1,861,754

CALL DISTRIBUTING TELEPHONE SYSTEM' Filed Aug. lO, 1929 9 Sheets-Sheet 6 FIGHT INVENTOR MANFRED T. POWELL BYA ATTORNEY l June 7, 1932. w. T. POWELL 1,851,754

i CALL DISTRIBUTING TELEPHONE SYSTEM Filed Aug. lO, 1929 9 Sheets-Sheet 7 J s M L RELAY |N seeus wrm P\CK. UP CONTACTS BY wlHFKED "T POWELL 'Y ATToR EY June 7, 1932. w. T. POWELL 1,861,75f1

CALL DISTRIBUTING TELEPHONE SYSTEM Filed Aug. 1o, 1929 s sheets-sheet s INVENTOR WINFKED T. POWELL lav/awww# ATTORNEY GROUP June 7, 1932. w, T, POWELL 1,861,754

CALL DISTRIBUTING TELEPHONE SYSTEM Filed Aug. l0, 1929 9 Sheets-Sheet 9 I Z 5 o GROUP 5 L EV Hm@ `Hlo7 H E E. RELHYS l a 3 w GROUP z r H H H Fl GA O |04 los COMMON ALLOTTER Patented .lune 7, 1932 UNITED s'nxfr-lssv -PA'rlszNr oFFicE* i WINTER/ED A'Vl. POWELL, OF ROGHESTER, NEW YORK, ASSIG-NOR TO THE STROMBERG- oAnLsoN TELErHQnE MANUFACTUMN CORPORATION QF .NEW YORK f CALL DISTRIBUTI-NG TELEPHONE lSYS'JEIVI Application filed August 10, 1929. Serial No. 384,943. 'i

This invention relates to telephone systems and more particularly to interoiiice `telephone systems. Y l

In earlier telephone systems it was the practice to employ a 4so-cal-led order wire be# .a calling line Yat the originating oiiice. Later such systems were improved by an arrangement known in the art as straight `forward trunking wherein theoperator-at-the originating otiice, known as theAoperator,selected an idle trunk leading to 'an idle operator at the terminating office and instructed this operator who was automatically connected. to thev selected trunk7 as-to thenumber of the wanted line. Such an arrangement has greatly improved the'operation 'of interoiiice tele-V phone -systems but still has ynot overcome all the .diiiiculties offormer systems. One-of these difficulties arose from *the fact that originating calls were indicated -by line lamps A appearing at ,anv operators position and since there was no means for indicating the order in which the calls-were originated, it frequently happened thatcertain calling lines were answered out of turn with the result that certain other calling lines were unduly delayed in receiving attention. In order Ato overcome this disadvantage it is proposed to employ automatic `switches and associated means for distributing calls to answering operators. While automatic switches have been suggested for this purpose it has been customary to provide switching equipment to take care of the maximum number of s1- multaneous calls, however, 1n accordance with the present invention a smaller number of automatic switches are used to distribute calls to operators but in addition-the manual switchboard with its line lamps is retained and when a predetermined number of simulltaneous calls are originated the presencev of combination of calldistribution to the A operators of the in teroitce system together with the provision for automatically yconnecting the B operators to extended trunks in accor-dance with a predetermined sequence.

In the drawings Fig. l indicates a schematic showing of one possible layout of automatic switches `for distributing calls from'la group of subscribers? lines to A operators` positions; Fig. 2 shows one possible layout of the operators positions atan originating or A switchboard as well asvtheterminating' or B positions of a switchboard at a vdistant otlice together with thetrunk groupinglbetween these oiiices; Fig. 3 is a chart showing the arrangement of the remaining tigures in Vwhich Fig. e shows cer-tainjgroups of relays G COMPANY, 0F ROCHESTER, NEW YORK, A Y

control the selectionof trunks terminating Vat these positions Fig. 5 shows a callin g rsubscribers line Yand a series of switches for eX- tending such a line to an operators position;

Fig. 6 indicates a plug-ended trunk lat the selected operators position by which calls may be extended vto subscribe1s-lines ter,

minating at this ofiice or by which these calls may be extended to a. distant oilice; 1F`ig."f7 shows some of the common equipment associated with the plug ended trunk of Fig.;6; Figs. 8 and 9 represent thev operators equipment at the terminating otlicey while Fig. l0 is a schematic showing of andarrangef ment whereby lamps at the A switchboard' associated `with trunks vleadingtoY adistant oftice indicate a trunk designated for use Where by it is. unnecessary Yfor an operator to test the various outgoing trunks before they can be used i For purposes of this descriptionit is assumed, las represented in Fig. 1,v thatV there are k.5

630 lines such as A which have access to three A operators positions designated -O'jP'and that there are thirty trunksT Ktermin ating at each ofthese positions. For convenience the lines are divided into lifteen groups of forty-two lines each, each group being served byseven iindersdesignated -F associated 'with' sevenv primary selectors P `S while a single finder allotter F A is provided for each group of linders. *The terminal banks offthe priico( mary selectors P S are multipled together and are connected through trunks to ninety secondary selectors S S in three groups of thirty each. These trunks may be connected through an intermediate distributing trame I D F, if desired. The multipling is so arranoed that any primary selector and kany calling line may have access to any idle trunk at any A operators position. l There is associated with each A position a trunk allotter T A which functions to allot trunks leading to its associated position in rotation.

It is believed that the invention will best be understood by describing certain types of telephone connections. When a subscriber at A originates a call by removing his receiver from its switchhook, the line relay 5 is energized over the two sides of the calling line in series, through the back contacts of the cut-oil' relay 6. The line relay is thus actuated and closes an operating circuit for the relay 7 of the finder allotter, from ground, front contact of relay 5, winding of the relay 7, armature and back contact of relay 7, armature, backv contact and winding of the motor magnet S to grounded battery. The operation of this relay is eiiective toclose a driving circuit orthe motor magnet 9 of the linder switch, traceable-from ground at the inner armature and back contact of relay 10, winding, arma ture and back contact of motor magnet 9,

finder allotter brush 11, inner front contact and armature of the start relay 7, resistance,

to grounded battery. Under the control ot` this ycircuitthe motor magnet 9 'advances the brushes of the finder until its test brush 12 encounters the test terminal 13 of the calling line A, indicated by the presence of ground potential. When the calling line test terminal is thus tested, a circuit is closed from ground at the armature and front 4contact oi line relay 5, test terminal 13, test brush 12, allotter brush 14, winding of the relay 15, inner front contact and armature of relay 7, resistance to grounded battery. It will be noted that this last described circuit is in shunt of the driving circuit of the motor magnet 9 so that this magnet no longer advances the inder brushesbut the relay 15, however, is operated. Y

The operation of start relay 7 also closes a driving circuit for the motor magnet 16 of the primary selector, from ground, lower armature and back contact of relay 10, winding, armature and back contact of motor magnet 16, iinder allotter brush 17, front contact and armature of start relay 7, resistance to grounded battery. Under control of this cir.- cuit this motor magnet advances the brushes of the primary selector until its test brush 18 finds the test terminal 19 of an idle trunk whereupon the relay 20 of the nder allotter is operated from grounded battery,resistance, outer armature and contact of relay 7 winding of relay 20, allotter brush 21, primary selector test brush 18, test terminal 19, lower armature and back contact of rela-y 22, outer, back contact and armature of slow releasing relay 23, conductor 24, back contact and armature of relay 25,l which relay is common to comes busy, that is when the operators tele-.

phone set is connected to a telephone line, relay 25'is energized and the stopping ground for the secondary selectors reaching this position, is removed and transferred to position 2. If position 2 is likewise in use, the stopping ground for the secondary selectors is removed by theoperation of relayl 146. `While, if position 3 is engaged,rthe relay l151 is likewise operated to remove the stopping ground so when any operator removes her telephone set from her position, the induction coil relay 26 deenergizes and makes that position unselectable. Vhen all three positions are busy, stopping ground is again extended to all positions so calls 4"will come in .to all of them. Y The control circuits of Figa are so arrangedthat during Vlight trailicl periods, when one operator is handling calls for all three positions and vis stationed at position 2, for example, calls normally come to that positio-n. Under this condition when all trunks at position 2 are in use, -relay 148 energizes and extends the stopping ground to the trunk of position 1 even though the induction coil relay 26 is deenergized. This allows calls to reach position 1. When all the4 trunks at positions 1 and 2 are busy, the stopping ground is extended to position 3 and calls are thereupon routed to this position. Referring to Fig. 6 it will be seen how relay 149 is operated when all trunks are busy. vAs long as there is an idle trunk there will be ground on commonconductor 150, applied either at the left hand armature and back contact of relay 44 orat the lower back'concontact and armature of relay 7 2.

Y As soon as both relays 15 and 2O are operated the switching relay 10 of the finder switch is actuated from grounded battery, through its lower winding, allot-ter brush 2T, inner, front contact and armature of relay 20, inner front contact and armature of relay 15, -to ground. rlhe allotter shown in the lower left hand corner of Fig. 5 is normally standing with its brushes in a position to allot an idle linder for use and as soon as the allotted finder is taken for use, the allotter advances to an idle position. In the case of the finder used in connection with a call just described, as soon as the switching relay is operated and when the cut-oit' relay 6 has operated to release the line relay 5, which in turn deenergizes the start relay 7, the motor magnet 8 has its operating circuit closed so that it proceeds to hunt for a-n idle iinder, This circuit is traceable from grounded battery, winding, back contact and armature of the motor magnet 8, armat-ure and back contact of relay 7, armature and back contact of relay 15, allotter brush v4,

inner frontl contact and armature of relayl 10, to ground. The allotter is thus advanced until its brush 4 encounters a terminal not connected to ground indicating an idle finder, at which time the allotter ceases to operate. In the event that all the finders of a. group are busy, relay 145 -is operated since it is no longer short circuited by ground at a lowermost back contact and armature oi some one of the switching relay 10 of the gro-up. 1With i the relay 145 operated, the allotter will come to rest with its brushes in engagement withthe last set of terminals ofthe sets engaged by the allotter brushes and a break point in theI circuits for the multiple switchboard lamps 146 is closed. Thus when a line relay such as 5 is energized, the associated lamp 146 is lighted as a signal to the operator to complete the connection in the multiple. A switch 246 is provided so that the calls can be made to appear in the multiple even when all of the finders are not engaged.

When the switching relay 10 is operated,

as previously described earlier in this description, the calling subscribers line is extended Y through the finder brushes 29 and 30, upper armature and front contacts of relay 10, primary selector kbrushes 31 and 32, uppermosty armature and back contacts of relay 22, through both windings in series of the relay 33, to ground and grounded battery. Arlhe relay 33 is thus energized and at its armature and front contact completes an operating circuit for .the slow releasing relay 23. This' relay closes a holding circuitfor the cut-oit relay 6 and the switching relay 10 traceable from grounded battery, resistance, armature and front Contact ot' relay 23, primary selec- 'tor brush 34, innermost, upper front contact,

armature and upper winding of relay 10, 4its r lower front contact and armature to ground'.

A circuit, in multiple of that just described, is extended through the finder brush 28 and the cut-off relay 6, to ground. y

The relay 23 alsocloses lan operating circuit for the motor magnet 35 of the secondary selector, traceable from grounded battery, re-

sistance, middle armature and contact of rei lay 23, back contact, armature and winding of motor magnet 35, front contact and armature of the relay 23, inner back contact and armature of relay 22 to ground. Under the con-y trol of this circuit and motor magnet 35 advances the secondary selector brushes 36 to 39 inclusive until the test brush 39 engages the test terminal 40 of an idle trunk leading to an A operators position. kAs soon as this test brush encounters the test terminal 4D, the motor vmagnet 35 is shunted and the switching relay 22 operated in a circuit completed from grounded battery, resistance,l middle armature and front contact of relay` 23, upper winding of the relay 22, test brush asl 39, test terminal 40, brush 42 of the trunk al- Y Y lotter to ground. Y

The operation of the switching relay 22 connects the extended conductors of the calling line Vto the'brushes 36 and 37 and thence through the upper and lower windings Vof the.

repeating coil and lboth windings in series of mary switches is also extended atthis time f through the innermost upper armature andV Y front contact ot relay 22.

Also when the relay 44 is operated, it advances the trunk allotter toa position to allot an idle trunk byclosinga circuit for the relay 42Vfrom grounded battery, winding of this relay, allotter brushV 46, left hand front contact and armature of relay 44 to ground. The relay 42 energizes and disconnects the stopping ground from 'the test terminal such as 40characterizing an idle trunk and at its right hand armature it extends an operatin circuit for the'motor-magnet 47 of the yall-otter which'is in multiplezwith the energizing circuit of the relay. Under the control of'this circuit the motor magnet 47. advances the ltrunk allotter-brushesuntil the brush 46 encounters a terminal characterized by the absence of potential which indicatesthat its related trunk` is idle.

It no other call is in the process of being f extended at this operatorsposition, at the time when relay 44 is energized, this` relay completes a. circuit from ground, its outer armature and front contact, middle armature and b ack contact of relay 48right hand Winding of the marginal relay 49, conductor 50, left hand winding of the relay 51, conductor 52, back contacts and continuity springs of relays 58, 54, and 55, conductor 56, left hand backcontact and armature of slow releasing rela-y 59 to grounded battery. The chain circuit Just described includes relays 53, 54, 55, etc., each of which is individual to one trunk of this group and this circuit is so arranged that if the relay of any trunk in this group is operated the corresponding relays of other. trunks thereof appearing in the chain are disabled. By such an arrangement the calls are distributed in sequence to an idle operator.

The relay 5l is energized in this last described circuit'but the marginal relay 49 is not operated owing to the high resist-ance of the left hand Winding of relay 5l. However, as soon as the relay 5l is operated it actuates the low resistance, slow releasing relay 57 from grounded battery, Winding of this relay, continuity spring and back contact of the relay 58, innermost right hand armature and contact of relay 51, the low resistance winding of this relay and thence to ground over conductor 50 and the remainder, ofthe circuit previously described. The operation of the relay 57 causes the energization of the slow releasing relay v59 from groundedy battery, winding of this relay, right hand Vfront contact and armature of relay 57 to ground.

' rlhe operation of the relay 59 at its left hand contact and armature opens the sequence 'circuit previously described to prevent any other trunks from operatinguntil the present trunk connection is ext-ended. l Y

The actuation of marginal relay 49 closes a break point in the operating circuits of theY ringing frequency selecting relays 73 and 7 3 by energizing slovv releasing relay 72. Relay 49 is also effect-ive to connect the operators telephone set and the common Ykey equipment shown in Fig. 7 to the trunk that is now being extended. The opera'tors telephone set (not shown) is ext-ended over the' conductors T and R to the trunk connected to the calling telephone line, conductor T being extended from the outer armature and back contact of relay 60, middle armature and front Contact of relay 4, left hand, back Contact and armature of slow releasing 6l, conductor 62,1front Contact and armature of relay 49, and thence to theleWer right hand Winding of the repeating coil. Ccn ductor R is extended from the right hand back contact and armature of relay 60, inner val a* nel j front contact and armature of relay 4,

through the condenser, rightliand back contact and armature of relay 6l, conductor 64, front contact and armature of Yrelay 49, upper right hand Winding of the repeating coil.

" As soon as the operators telephone set is thus connected to the trunk taken for use, and thereover to the calling subscribers line, the operator inquires the'number of the Wanted subscribers line.

The ringing equipment associated with the trunks at this operators position is arranged so that the selected ringing key may be operated prior to or subsequent to the insertion of the plug P into the jack of a subscribers line which terminates at the originating ofiice or in the jack of a trunk leading to` a distant office. Let it be assumed that the Wanted line is the one Whose substation is indicated as B in the upper right hand corner of Fig. 6. The operator thereupon tests this line by touching the tip ofthe plug P to the sleeve of the jack J and in the absence of a busy condition, indicated by the sound of a click in the` operators head set, she inserts this plug into the jack'J. This operation causes the energization of sleeve relay 79 in series with cut-off relay 142 and relay 79 in turn completes a circuit for energizing slow releasing relay 7'7. If the proper ringing frequency has not previously been selected, the operatordepresses some one of the keys 65 to 68 inclusive, such as key 67 of Fig. 7. This operates the sloW releasing relays 69 and 70 inseries through the contacts of key 67, which effects the operation of the ringing frequency relay 7 3 (Fig. 6) from grounded battery, its right hand Winding, innermost front contact and armature of relay V7 2, conductor 74, outer armature and front contact of relay 7l, right'hand front Contact and armature of relay 69 to ground. The relay 73 on operation closes a locking circuit for itself through its left hand Winding, its left hand front contact and armature, inner front contact and armature of relay 7 5, conductor 76, to ground at the right hand front Contact and armature of relay 44. Ringing relay 75 is operated at this time from grounded battery, its lower Winding, front Contact and armature of relay 72, conductor 180, outer right hand, front contact and armature of relay 71, left hand front contact and armaturevof relay 69 to ground.

Ringing current is then applied from the 66 cycle source through the back contact and armature of relay 7 3, the right hand front contact and armature of relay 73, inner lowerarmature and front contact of relay 77, Winding of the trip relay 78, loWermost front Contact and armature of relay 75, ring contacts of the plug and jack. over the side of the subscribers line and substation equipment including the ringer, over the other side of the subscribers line, tip contacts ofv the ack and plug, upper armature and front contact or" the sleeve relay 79, inner, upper armature and front contact of relay 75 to ground. Vhen the subscriber at B removes his receiver from the switchhook in response to the switchhook, the supervisory relay 43 deenergizes thereby lighting the disconnect lamp 81 in a circuit traceable from grounded battery, lamp 81, armature and back contact of the relay 82, innermost armature and back contact of relay 49, upper armature and back` contact of relay 43, frontcontact and armature of sleeve relay 79 to ground. On notingY that the lamp 81lis1steadily lighted, the operator removes the plug P from the jack J thereby permitting the equipment tobe restored to normal; The deenergization of the relay 43 thereupon causes the deenergization of the slow releasing relay 44V which in turn at its inner armature and front contact, re-

moves holding battery from ,the circuit which has been holding the iinder and ,primary and secondary switches operated. These switches thereupon are released.

' Let it now be assumed that the subscriber at A had desired to call a subscriber at .the

'distant oiiice. In previous systems it has been necessary either for the operator at the originating oice to have a trunkassignment transmitted from the terminating oiice lover an order wire or else it was necessary for the originating operator to test all the outgoingv trunks leading tothe terminating office by touching the tip of the plug P to the sleeves of jacks such as J leading to this oiiice. In accordance with vthe present invention pro vision is made so that an idle trunk to the wanted office is indicated by the presence of a lighted lamp associated with the jack ot such idle trunk. v

For purposes of this description it is assumed that there are fifteen sectionsl or operators positions in the originating ottice (Culver) and that there are lthree positions in which trunks from this oice terminate at the terminating -ofce (Glenwood). It is also assumed that there are thirty trunks extending between the originating and termiy nating oh'ices. It will be understood of course that these numbers .are merely for purposesV ot illustrationvand --may be varied as traffic requirements demand. In the following description it .will be seen that the trunk indication given to the originating operator is such that there is an even distribution of calls to the positions at vthe terminating othce. In addition there is provided means wherebythe idle trunksV infeachgroup are indicated to the originating operator in consecutive order,

that is, they are assigned in rotation by means i of a rotary stepping switch which makes a progressive trip over all of the trunks in the group and then starts at the beginning again. This arrangement provides even wear on the trunk jacks and permitsva Vmore uniform answering time so that the possibility of delay at the terminating end, due to calls being answered out of turn, is greatly reduced;

In F1g.- 10V there 1s disclosed a schematic showing ci?Y this arrangement in which one rotaryswitch is provided for each'group of trunksatthe terminating oHce and since it is assumed that there are only three groups of trunks, there are three of these switches. In addition there is provided one rotary stepping switch which is common to allof the Y sections in the originating oliice so' that a total of :tour rotary switches are provided. The switches associated with the groups have eleven terminals each since it is Vassumed that therea'reten trunks in each group, while the common f. switch has seven-terminals. r For purposes of this description it is assumed that all of the terminating operators are idle, that all trunks are idle, and further, that the group switches are standing in the positions shown in F ig. 10. Since all positions at the terminating otlice are idle, relays 83,` 84, and 85,` are in their normal condition.A It will be understood that these relays are the remote control relays which are operated whenever their corresponding terminating positions become busy y With these relays in normal condition all of the differential relays 86,87,

4and 88 will likewise be in their normal condition so that the relay 89Y will be energized from grounded battery, resistance, its left hand winding, continuity spring and back contact, brush 90 in position 1, back contacts and armatures of relays 86 to 88 inclusive' to ground; The energization of relay 89 is held operated over 'the previously described circuit now including both of its windings in series. At this time a circuit is effective from ground, brush 92 in positionl, brush 930i the switch associated with group 1, conductor 94, lamps 95 in sections 1, 4, 7, 10 and 13 associated with the jacks J of the idle trunk to grounded battery. The lighting ofthe lamps`95 indicates that the trunk-terminating in the jacks J is idle. Acircuit is also ef-v fective. from ground at brush 96 in position 1, brush 97 and the iirst lamp 98 of group 2 at positions 2, 5, 8, 11 and 14. This indi'- cates the idle trunk in the second group. Like- Vwise a circuit is eliective from ground,rbrush '99,in position 1, brush 100 in position 1, and

lamps 101 associated rwith the irst trunkv in group3 atfpositions 3, 6,9, 12 and 15. When these trunks are taken Aby the originating operators, their corresponding relays such as `102, 103,104, 105,106,107, etc. will be operated `and as each such relay is energized, Va

circuit is closed fromV ground either byway 'iso .y as

of one of the brushes suchas 139, 140 or ,141, back contact, armature and winding of the motor magnets such as 1018, 109er 110 to grounded battery.` In this way the switch associated with each group of trunks is progressively advanced to idle trunks. If a trunk in group 1, Jfor example trunk #1 is chosen, its sleeve relay 102 is operated to cause the motor magnet 108 to advance its switch brushes to'trunk #2. It will be noted later in this description that the relay is energized at relay 182'(Fig. 9) over-con 'ductor 181 when the operators telephone set at terminating position 1 is connected to a trunk and this relay closes a circuit through the lower winding of the differential relay 86 to battery. This relay energizes .and thereby extends -a circuit from ground through the lowermost armatures and bach contacts of relays 87 and 88, its lowermost contact and armature to position 2 of brush 90. Since the locking ground is removed from the windings of relay 89 by the operation of relay 86, relay 89 deenergizes and thereby permits the motor magnet 91 to advance the brushes of its switch to position 2 where the ground applied by the energization of relay 86 to the position 2 ot brush 90 is eilective to shunt the motor magnet 91 and stop the switch in this position, moving brush 92 to position 2. Relay 89 is operated in this position of the switch and is locked operated as previously described. With the brushes 96 and 99 also moved into position 2 their circuits in position 2 are not changed since terminals 1 and 2 at brushes 96 and 99 are multipled together. Brush 92 however disconnects ground from brush 93 of the switch associated with position 1, which brush controls the lamps in group 1 in sections 1, 4, 7, 10, and 13', and connects ground to brush 111 which ground extends by way ot position .1 of this brush and the iirst lamp of group 2,V

at sections 1, 4, 7, 10 and 13. If the operator at position 2 is busy, relay 84 is operated and at its upper armature and front contact closes a circuit including the lower winding of relay 87 to grounded battery. Relay 87 voperates and extends ground through the lower armature and back contact of relay Y 88, the lower armature and Contact of relay 87 ,armature and back contact of relay 86, to position 3 of brush 90. Relay 89 deenergizes, as before described.` whereupon the motorv magnet 91 advances the brushes of its switch into position 8 where relay 89 is then operated. Brushes 92 and 99 are wired the same as in position 1. Therefore the idle trunk in groups 1 and 3 will be indicated at the same sections as when all B positions are idle. Brush 96 at position 3 connects ground by Way of brush 112 to the idle lamps at group 3 in sections 2, 5, 8,11 and14. This removes the idle trunk indication in group 2 and extends it to idle lamps inv group 3 at Ycommon switch to position 1.

sections 2, 5, 8, 11 and 14. When the operator at position 3 is busy, relays 83 and 88 will be energized and the latter will extend ground to position 4 of brush 90 which will cause the common switch to advance to position 4 where brush 99- will shift the idle lamp indication from group 3 at sections v3, 6, 9, 12 and 15 to group 1 at these sections.

lFrom the above, it will be seen that as each the common switch Yto go to position 5. In position 5, brushes 92, 96 and 99 are eective to shift the idle indication of groups 1 and 2 to group 3 at sections 1, 2, 4, 5, 7, 8, 10, 11, 13, and 14.

When B positions 1 and 3 are busy, relays 85 and 83, 86 and 88 are operated .to advance the common switch to position 6. In this position. brushes 92, 96, and 99 are effective to give the indication in group 2 at sections 1, i, c, 7, 9, 10, 12, 13 and 15. y Y

When B positions 2 and 3 are busy, relays 84, 83, 87 and 88 energize to advance the common switch to position 7. In this position, brushes 92, 96, and 99 are eftective to` shift the idle lamp indication of groups'2 and 3 to group 1 at sections 2, 3, 5, 6, 8, 9, 11, 12, 14 and 15.

When all three of the B positions are busy, relays 83, 84, and 85 are operated. The lower windings of 86, 87 and 88 are energized `from contacts of corresponding relays 83, 84 and 85. With these last mentioned relays energized chain circuits are closed for energizing the upper windings of relays 86, 87, and 88. Since these latter relays are differential, they will all deenergize and being in their normal positions, a circuit is eective to advance the Y Under this condition, the lamp indication is the same as when all B positions were idle, but there is, of. course, a delayed cut-in at the B end.

As B positionsnow become idle, the Colnmon switch will be advanced to the proper position for indicating at all sections at the A end by means of the lamp, just which B position is idle. i

It has previously been assumed that the lamp associated with trunk jack J is n ...lv

common equipment whichpconnects an oper ators telephone set to the trunk Just seized and associates the common ringing equipment with this trunk. This is accomplished in al circuit traceable `from ground, middle arma ture and front contact of relay 127, armature and back contact of relay 128, back Contact and armature of relay 130, left hand winding of marginal relay 131, conductor 132, left hand winding of relay 133, armature and back contacts of chain relays 135, 136, 137 to grounded battery. Relay 133 is energized in thisV circuit but the marginal relay 131 is 'Y not operated at this time. The operation of relay 133 eifects the energization of the slow releasing relay 13aL from ground, continuity spring and front contact of relay 133, winding of relay 134 and thence throughthe con tacts and armatures of relays 135, 136 and 137 to grounded battery. Relay 134, when operated, substitutes the right hand low resistance winding of relay 133 for the left hand high resistance winding ofthis relay which was previously connected in circuit with the marginal relay 131. Relay 131 therefore operates at this time. The slow releasingrelay'139 is then actuated in a circuit completedat the inner right hand armature and contact of relay 131, to associate the common ringing equipment with the trunk circuit taken for use. At the left hand armatures and contacts of relay 131 the operators telephone set is connected in series with the right hand windings of the repeating coil.

At this time relay 153 of Fig. 9 is energized from ground at the armature and front contact of relay 154 which relay is normallyT energized during the period that the operators telephone set is connected to the circuits of her position, conductor 155, winding of relay 153, conductor 156. inner lett hand contact of relay 131 through the winding of the repeating coil to grounded battery. Relay 153 effects the energization of the relay 157 which in turn operates the relay 158 from grounded battery, its winding, armature and front Contact of relay 157, lower armature and back contact of relay 159 to ground. Relay 158 then causes the operation of rela-y 160 and this relay in turn energizes the re-V tacts of relay 162, Jfront contacts and arma-` tures of relay 159 and thence over conductors 156 and 163, left liand armaturesand front contacts of relay 131 to the right hand windings of the repeating coil.

On receiving the call passing tone the A nation of the wanted telephone line which is assumed to be the line whose multiple jack is indicated at J2. The operator then touches `the tip of the plug P2 to the jack J2 and in vthe absence of a distinctive click, known as a busy signal, the operator inserts the plug into the jack J2. This is eective to energize the sleeve relay of the operators'circuit and the cut-o relay in a circuit extending from ground, winding .of the cut-oftrl v'relay 1611, sleeve contacts of the ack and plug, winding of the sleeve relay 165to groundedvbattery.

As soon as the marginal relay 131 is operated it edects the energization of the slow releasing relay 139 which associates the common key equipment of the operators position with the trunk circuit of Fig. '8. With the sleeve relay 165 energized, a circuit is closed for operating the slow v'releasing relay 166 to close a breakpoint in the tip conductor. The relay 166 also closes a circuit to actuate therelay 168 from grounded battery, through Yoperator informs the B operator of thedesigl the intermittently closed contacts of the pickup device, continuity contactand spring of relay 168, winding of'this relay, inner front contact and armature of relay 166 to ground.

Y.Relay 168 when operated closes a locking cir cuit for itself from grounded battery, its

armature and continuity spring and thence over the remainderof the circuit to ground at the front contact of relay 166. The operator then depressessome one of the ringing 'keys shown at Vtheright of F ig. 8. Let it be assumed that ringing key 169 is-depressed whereupon the slow releasing ring current selector relay.. 170 is energized. Vhen the relay 179`is energized, it closes an'operating -circuit from grounded battery, right hand winding of the relay 128, right hand winding and armature of relay 139, inner front contact and armature of relay 170, to ground. This energizes relay 128 to open a break point in the circuit of the incoming disconnect lamp 17 9. Relay 128 when operated closes a locking circuit for itself from grounded battery, through its right hand winding, its front contact and armature, front contact and armature of sleeve relay 165, outer armature and' front Contact of relay 127 to ground. The

energization of the relay 128 opens the operating circuit of the marginal relay 131 to permit therelease of the common operators se-. quence cut-inequipment of Fig. 9. With the Vrelease of the relay 131 the common equipment'including the operators listening circuit is restored to normal.

As soon' as the relay 170 is operated, the v ringing frequency'selectingrelay 171 is energized from grounded battery, its winding, armature and front contact-of relay 139, conductor 172, left hand front Contact and armaright hand armature and contact of relay 168,

winding of relay 174, armature and back contactrof relay 175, armature and back contact of relay 177, outermost armature and contact of relay 128 to ground. Ringing current of the proper character' to signal the called subscriber is now applied from the negative source, left hand winding of relay 177, right hand front contact and armature of relay 171,-

armature and back contact of relay 178, inner, lower contact and armature of relay 17 4, ring contacts of plug P2 and jack J 2, the lower side of the subscribers line and substation circuits in series, over the upper side of the subscribers line, tip contacts of the plug and Jack, armatures and front contacts of relays 166 and 174, inner, back contact and armature of relay 178, to ground. When the subscriber answers the call by removing his receiver from its switchhook, the relay 177 is energized and removes the short circuit about the relay 175 which is now operated from grounded battery at the armature and front contact of relay 168, windings of the relays 174 and 175 in series, armature and front contact of relay 128, to ground. This short circuits the ringing relay 174 causing it to deenergize so that there will be no further application of the ringing current during this call. Talking battery is supplied to the called subscriber through the right hand windings of the repeating coil.

At the close of the conversation, when the calling subscriber replaces his receiver on the switchhook, the A operator receivesithe disconnect signal in the manner already indicated whereupon she removes the plug P from the jack J1 resulting in the release ot the relay 126 which whereupon eii'ects the release of the slow releasing relay 127 The disconnect lamp 179 is then lighted from grounded battery, lamp 179, armature and back contact of relay 128, armature and back contact of relay 131, inner armature and back contact ot relay 127, left hand front contact and armature of relay 165 to ground. The lighting of this lamp is the signa-l to the B operator to remove the plug P2 from the jack J2 whereupon this operators equipment is restored to normal.

@kurt of operation of common aZZoter (Fzg-10) busy.

The common allotter is in position 4 when B position 3 is busy-also when all B positions are busy and all trunks in group 3 are busy.

The common allotter is in position 5 when B positions 1 and 2 are busy-also when all B positions are busy and all trunks in groups 1 and 2 are busy. Y

The common allotter is in position 6 when all positions 1 and 3 are busy-also when all B positions are busy and all trunks in groups 1 and 3 are busy. f

The common allotter is in position 7 when B positions 2 and 3 are busy-also when all B positions are busy and alltrunks in groups 2 and 3 are busy. Q

The commonY allotter is in position 1 when all trunks in all groups are busy.

lha-t I claim is: Y

1. The method of handling telephone calls which consists in automatically distributing each of a predetermined number of simultaneous callsv individually to certain operators and extending each call exceeding said Ypredetermined number to a plurality of operators.

V2. In a telephone system, a plurality of telephone lines, operators positions provided with jacks in which said telephone lines'terminate, a lamp associated with each jack, operators answering equipment, means responsive to the initiation of a predetermined number of calls on said lines for extending lines to idle operators equipment, means for operating the lamps of call originating lines at said positions for all calls exceeding said predetermined number.

3. The method of handling telephone calls which consists in automatically distributing each of 4a predetermined number of simultaneous callsindividually to a different operator, and extending each call` exceeding said predetermined number to all of said different operators.

4. In a telephone system, a plurality of telephone lines, operators7 positions provided with acks in which said telephone lines terminate, a lamp associated with each jack, operators answering equipment at each position including sources of ringing current of different character and a single ringing key common to' each position for each source of ringing current, means lresponsive to the initiation of'a predetermined number ot calls on said lines for extending each line to different 'idle operators equipment, means. for operating the lamps oflines at said positions for all calls exceeding said predetermined number, outgoing linesan'd means including operators answering equipment for extending a calling telephone line to a desired outgoing line.

5. In a telephone system, a plurality of telephone lines, operators positions provided with jacks in which said telephone lines terminate, a lamp associated with each jack,

operators answering equipment, means in-` cluding automatic switches and trunks ,re-

sponsive to the initiation of a predetermined numberof calls on said lines for extending each of said calling lines to different idle operators equipment, means including an allotter for assigning idle trunks for use, and means responsive to the operation of said allotter through a predetermined cycle for rendering said .lamps operative when their associated lines originate calls.

6.In a telephone system, a plurality vot telephone lines, a plurality of operators positions provided with jacks in `whichl said telephone lines terminate, a lamp associated with each jack, finder switches having fixed terminals in which said lines terminate, each finder switch beingprovided with a set ofv brushes, a selector having its brushes linked by atrunk to the brushes otsaid iinder, an

allotter for assigning idle finder switches for use, means including an allotted finder an associated selector for extending a calling line to'an idle operators position, means responsive to the allotting of a predetermined number of finders for use, for ren-dering the Y linked thereto, a plurality of secondary selectoi's accessible from said primaryl selec tors.I a plurality of trunks terminating in said sccondary'se-lectors and said operators positions, an allot-ter for assigning idle finders for use, a second allotter Vfor assigning idle operators positions for use, and means o-perative in response to the assignment of aV predetermined number of Vfinde-rs for use for rendering the lamps associated with the re! maining telephone lines opera-tive on the initiation of a call thereover.

8. In a telephone system, a plurality o telephone lines, a plurality of primary operators positions, a plurality of secondary operators positions, trunks interconnecting said primary and'said secondary positions, means for visually assigningk different trunks in a predetermined sequence at different primary operators positie-ns, and means for interconnecting a calling' telephone line with an as# signed trunk. Y Y

l9. In a telephone system, a'plurality of telephone lines, operators positionsp-rovided with jacks in which said lines terminate, a lamp associated with each jack, trunks tei'- m-inating at said operators positions and leading to a distant oiiice, means forvisually assigning idie trunks. for use-in sequence, means for automatically trunking a predetermined number of simultaneous ,calls to saidopeiators positions, andmeans responsire to such extensionof a predetermined number of calls for rendering the lamps of the remaining telephone lines operative ons.

the initiation of a call thereover.

. l0. In a telephone system, aplurality of 'telephone lines, A1 operators Apositions provided with'j acks in which said lines terminate,

al lamp- 'associated with each jack,trui'1kster-Q minating atsaid .A operators positions and leadingto a distant ofiice, B operators vpositions at said distant oiiice in which said'trunks terminate,a plurality-ofsources of ringing current of different character-and a single ringing key for each source of current com-` mon to all trunks terminating at saidA B" operai tors positions, means for visuallyv assigningv Yat'A operators positions idle, trunks for use in sequence, lmeans p for mechanically extending calling telephone lines tofidle A operatorsl positions,.and means'responsive to vsuch extension of a predetermined-number `ofcalls for rendering the lamps of the remaining telephone lines'operative on the initiation Vof -a callthereover. Y

x11. In atelephone system, aV plurality oi.

telephone lines A operators; positions pro-- vided with jac is in which saidV lines terminat-e, a lamp associated with each jack, B. operators positions at a distant oiiice, trunks interconnecting said Aoperatorspositions and saidB operators positions,`means `for visually assigning at said A operatorspositions idle trunks for use `in sequence, means for automatically `extending a predetermined number of Ysimultaneous calls to said A `operators positions and means responsive to' such extension of a predetermined number of calls for rendering the lamps of thefremain ment-at the B operatorspositions and autofv matic means responsive to theextension ofla llO ing telephone linesoperative on the initiation 1 of" calls thereover, operators listening equip tending a predetermined nuimber of simultaneous calls to said A operato-rs positions, means responsive to the extension of a predetermined number of calls for rendering theA associate lampsv of the remaining telepho-ne lines operative in response to the initiation of Y means for connecting the trunk of an extended call to a called one of said-last mentioned lines. v"13. In a telephone system, a plurality of telephone lines, a plurality of operators positions, means including non-numerical switches' and incoming trunks for automatically distributing calls rom said telephone linesto idle operators"positions, an operators telephone set at each position, automatic means for connectingfsaid telephone set to altrunk-over which 'a call is extended to said operators position, outgoing lines andout-V going trunks terminating at said positions,

means-at said positions for connecting an extended trunk to an outgoing line,a plurality of sources of ringing current, and'means including asingle ringing key common to the trunks of an Aoperators position Vfor connecting each Vsource of ringing current to any selected incoming trunk, and'means for assigning outgoing trunks for use.

'14. In a telephone system, a plurality of incoming lines, a plurality of primary operators positions, means including automatic switches and primary trunks for distributing calls from said telephone lines to said operators positions, secondary trunks terminat-V ing in jacks in said operators positions-and leading to secondary operators positions, in-

' dicating lamps associated with said jacks, and

means for controlling said lamps in a prede.

termined sequence in accordance with the busy or idle condition of said secondary operators positions for indicating an idle secondary n trunk terminating therein, means for connecting a primary trunk to the jack of an indicated trunk, and means at said secondaryv positions for completing the extension of calls. n Y

15. In a Vtelephone system, aplurality of 'telephone lines, primary operators positions provided with jacks and associated lamps, lines terminating in said jacks, means including automatic switches and trunks for exlines, outgoing lines terminating inthe jacks at said primary operators-positions, lamps associated with said `iacks, secondary operators positions in which said outgoing lines terminate, means controlled in accordance with the busy or idle condition of said secondary operators positions for lighting said lamps to indicate idle outgoing lines leadingA to said positions, other telephone lines terminating at said secondary operators positions, and means at lsaid last mentioned positions for completing connections to said last mentioned lines.V f'

16. In a telephonesystem, a plurality of A operators positions, a plurality of telephone lines terminating thereat, a plurality of B operators positions, trunks each terminating in a plurality of A operators positions and in a B operators position,`means at the A operatorspositions forassigning trunks ina prearranged orderV in Vaccordance with the busy or idle condition of the B operators p0- sitions, means for extending a calling-telephone line to an assigned trunk, a plurality of telephone ylines terminating at said B operators positions, and means for extending an assigned trunk to a wanted one of said last vvmentioned-telephone lines.' Y

Y17.l Ina telephone system, a plurality of A operators positions, ya pluralityV of telephone li-nes terminating tliereat, Ya plurality of B operators positions, trunks each terminating in a pluralityof A operators positions and in a B operators position, an indicator associated with each trunk at each A operators position, said trunks-at vsaid A operators positions being arbitrarily arrangedin groups, means for operating the indicators of each group of A operators positions in a definite sequence inaccordance with the busy or idle condition of the B operators positions in which said trunks terminate, means for extending calling*v telephone lines kto assigned trunks, a plurality of telephone lines terminating at said B operators positions, and meansfor extending assigned trunks'to said last mentioned telephone lines. 1

18. The method of trunking calls between A operators positions and B operators positions,r which comprises assigning trunks of groups in sequence to said A operators, while any B operators position is idle, and then assigningtrunks in sequence to" said A'operators so that there is uniform distribution of,

calls to` the B operators,wliile.all of the B operators remain busy. i 19. Ina telephone system, a plurality of A operators positions, a plurality of telephone lines termina-ting thereat, a plurality of B operators positions, trunks each terminatingv in a plurality of A operators positions and in a B operators position, indicators associated With each trunk at each A operators position, said trunks at said A operators positions being arbitrarily arranged in groups, means for operating the indicators of each group oi' trunks of the A operators positions in a deiinite sequence to assign saidv trunks in accordance With the busy or idle condition of the B operators positions in which said trunks terminate, the operating means for said indicators functioning to uniformly assign trunks to said B operators positions when all of said B operators positions are busy, means for extending calling telephone lines to said assigned trunks, a plurality of telephone lines terminating at said B operators positions and means for extending assigned trunks to said last mentioned telephone lines. v

20. In a telephone system, a pluralityof telephone lines, a plurality of primary opererators positions, each provided With answering equipment, trunks interconnecting Wering equipment, trunks interconnecting said primary and said secondary positions, means for assigning different trunks in a predetermined sequence at diiierent primary operators positions, means for transmitting a signal over an assigned trunk when a secondary operators answering equipment is connected thereto, and means for extending a calling telephone line to-an assigned trunk.

21. In a telephone system, a pluralityof telephone lines, A operators positions, trunks terminatingat said A operators positions' and leading to a distant oice, B operators positions Vat said distant office in which said trunks terminate, a plurality of sources of ringing current of different character and a single ringing key for each source of current common to all trunks terminating at said B operators positions, means for Visually assigning at A operators positions idle trunks for use in sequence, means for me- Chanically extending calling telephone lines to idle A operators positions, and means for connecting an extended telephone line to an assigned trunk.

22. In a telephone system, a plurality of telephone lines, A operators positions, B operators positions at a distant ofce, trunks interconnecting said A operators positions and said B operatorspositions, means for visually assigningvat said A operators positions idle trunks for use in sequence, means for automatically extending calling telephone lines to said operators positions, means for connecting an extended telephone line to an assigned trunk, operators listening equipment at each B operators position, and automatic means responsive to the extension of a call over one of said trunks to a B operators i position at a distant oiice for automatically connecting said operators listening equipment thereto.

In Witness whereof, I hereuntoy subscribe my name this 9th day of August A. D. 1929.

WINFRED T. POWELL. 

